Climate Change Forces Decomposer Fungi To Focus On Survival

How decomposer fungi respond to climate change is important to creating more informative climate models.

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Decomposer fungi are central to breaking down dead material across ecosystems. As they do so, they move carbon in the soil back into the atmosphere as carbon dioxide.

Scientists have been focused on studying decomposer fungi to improve climate models because the activity of decomposer fungi can affect feedbacks between climate and ecosystems.

A new study released in Frontiers in Microbiology examines the activity of decomposer fungi under 10 years of warming compared to normal conditions. Greenhouses in Delta Junction, Alaska were set up to mimic warming in a boreal forest ecosystem.

In the greenhouses, air temperature was about 1.6 degrees Celsius warmer and the soil temperature was about 0.5 degrees Celsius warmer. Boreal forests are particularly sensitive to climate change and store large amounts of carbon in their trees and soils.

All organisms have a limited amount of energy that they need to divide between growth, survival and reproduction. Scientists from Mexico and the U.S. quantified how decomposer fungi spent their energy by examining the soil metatranscriptome. This technique captures fungal activity by decoding RNA, a precursor to enzymes and proteins of interest. They compared fungal activity between plots warmed by greenhouses and the corresponding control plots that were exposed to normal conditions.

Boreal forest in Alaska.

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The researchers found that groups of fungi known to have stress-tolerant adaptations to drying and other environmental stresses were more common in the warmed plots than the control plots.

They also discovered that fungi in the warmed plots were using their cell metabolic maintenance genes at higher rates than fungi in the control plots. Fungi are focused on surviving rather than decomposing dead material.

This is a clear example of trade-offs between survival and growth. We will likely see the fungi living in boreal forest soils prioritize survival rather than decomposition. At the same time, the fungal communities may become dominated by the fungal groups with stress-tolerant adaptations.

These shifts in energy allocation and the fungal community could change carbon cycling at the ecosystem-scale. Not only does climate change cause fungi to alter their activity, but fungi can also have impacts on climate via their decomposition activity.